Ocorrência e eficiência de populações de bactérias fixadoras de nitrogênio em feijão-caupi em Marabá, PA

Cowpea is a common legume in the northern and northeastern regions of Brazil. It has agreat ability to form symbiosis with bacteria fixing atmospheric nitrogen as one of the waysto increase crop productivity and to replace nitrogenous fertilizers. The present work aims toevaluate the occurrence and efficiency of populations of bacteria that nodulate legumes and fixN2 in seed of cowpea and cultivar BR 17 Gurgeia in an agroforestry system in Maraba, Para.Of Para Campus Maraba Rural in December 2016, in a Yellow Latosol, medium texture, in anarea without previous use of any type of inoculant with implantation of agroforestry system. Itwas used the seeds of cowpea creole known in the region as owl and the cultivar BR 17 Gurgueia.The nodulation and the biomass production of cowpea plants were evaluated at the timeof flowering. The plants cultivated with creole seeds and cultivar BR 17 Gurgueia presentednodulation. The efficiency of native populations in N2 fixation was similar regardless of seedtype. It is suggested the capture of strain in the study area for the evaluation of plant growthpromotion.